The installation of a shelf, cabinet, countertop or other fixture may include attaching a right angle bracket or corbel to a wall surface to support the fixture. This can be a time consuming task. Sometimes a wall cleat is installed, which may interfere with the bracket or corbel location. Often the wall surface is not true or vertical, leading to additional installation effort when attempting to provide a horizontal shelf or counter surface. Mounting a bracket in a vertical orientation can also be a time consuming task as well.